CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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either overlaps slightly or aligns with the edges of these contacts (self-alignment process). Self- alignment is preferable since it minimizes the parasitic gate-source and gate-drain capacitances.[33] Fig. 10. Schematic of a n-channel MOSFET. There are three operation modes for practical MOSFET devices. The first one is called subthreshold mode and it happens when the gate source voltage VGS is lower than Vth. Under this situation, due to the Boltzmann distribution of electron energies, there are still some high energy electrons that can flow through the channel and results in a leakage current. This current has been found exponentially dependent on the value of VGS. When VGS>Vth and the drain-source VDS voltage is less than the value of VGS-Vth, the MOSFET is in the linear mode. In this mode, the conducting channel is created for current flow from drain to source and the MOSFET operates like a resistor. The current is almost linearly dependent on VDS under a fixed gate voltage. By changing the gate voltage, the resistivity of the conducting channel is changed too. The third mode is saturation mode when VGS>Vth and VDS>(VGS-Vth). In this mode, the transistor is in its constant current region and is switched fully on. The onset of this mode is also known as 31
pinch-off to indicate the lack of a channel region near the drain. The drain current is now weakly dependent upon the drain voltage and controlled primarily by the gate source voltage (VGS). In the past few decades, the continuous scaling down of the MOSFET in size has revolutionized the development of the microelectronic industry. The channel length of the MOSFET structure has been shrinked from microns to tens of nanometers. At this scale, a lot more functionalities can be realized in a same size wafer and meanwhile the cost of fabrication can be decreased. However, with this scaling down, few operational problems have been found. For example, the voltage applied to the gate has to be reduced to maintain reliability. To maintain performance, the threshold voltage needs to be reduced too. With the reduced Vth, the transistor cannot be switched from completely off to completely on with the limited voltage swing available. Subthreshold voltage can thus consume as much as half of the total power consumption. Another problem is with the gate oxide layer: as the thickness of this layer going down to few atomic layers, the electron tunneling effect occurs and makes the power consumption even higher. High-k materials (such as hafnium silicate or oxide) have been developed to replace the traditional oxide material since the layer can be made thicker while maintaining the same capacitance.[34-36] To work with these new high-k materials, the properties of the gate electrode materials have to be considered as well. The traditional gate electrode material polysilicon, for example, when coupled with a very thin (~1 nm) dielectric layer, a phenomenon observed is poly depletion, where a depletion layer is formed in the polysilicon layer next to the dielectric layer when the transistor is in the inversion. To avoid this problem, metal gate materials such as tantalum carbide, tantalum nitride and titanium nitride can be used with high-k dielectrics.[37-39] 32
Page 1 and 2: CHEMICAL VAPOR DEPOSITION OF THIN F
Page 3 and 4: ABSTRACT Chemical vapor deposition
Page 5 and 6: DEDICATION This dissertation is ded
Page 7 and 8: φ In-plane tilt angle of X-ray dif
Page 9 and 10: ACKNOWLEDGMENTS It is my pleasure t
Page 11 and 12: CONTENTS ABSTRACT .................
Page 13 and 14: 3.2.1 Introduction ................
Page 15 and 16: LIST OF TABLES Table 1. Hafnium ami
Page 17 and 18: indicated by the complex FMR curve.
Page 19 and 20: Fig. 49. Ferromagnetic resonance cu
Page 21 and 22: growth rate, good step coverage and
Page 23 and 24: growth of thin film oxides due to t
Page 25 and 26: one can uniformly deliver precursor
Page 27 and 28: for the next reaction step as shown
Page 29 and 30: Fig. 3. Schematic of a typical dire
Page 31 and 32: is predominantly dependent on syste
Page 33 and 34: J r J A -D n b-n 0 δ n or for the
Page 35 and 36: surface passivation with certain in
Page 37 and 38: ay spectroscopy (EDS), Wavelength d
Page 39 and 40: incidence angle is larger than cert
Page 41 and 42: epresenting those characteristic ph
Page 43 and 44: 1.2.3.3 X-ray Diffraction (XRD) X-r
Page 45 and 46: exhibit diffraction peaks in the no
Page 47 and 48: (nanometers to tens of nanometers),
Page 49: strongest absorption of microwave s
Page 53 and 54: coupling is from unbound ferrite-fe
Page 55 and 56: diffusion barrier material in micro
Page 57 and 58: Fig. 14. A cross sectional scanning
Page 59 and 60: In spite of the same spinel structu
Page 61 and 62: ferrites has been investigated exte
Page 63 and 64: systems is showed in Fig.18.[83] As
Page 65 and 66: precursor vaporization process, e.g
Page 67 and 68: CHAPTER 3. PLASMA ENHANCED ATOMIC L
Page 69 and 70: the initial surface chemistry for t
Page 71 and 72: delay time of 2 seconds between spe
Page 73 and 74: Kcal/mol respectively. The stronger
Page 75 and 76: negative slope) behavior in the pum
Page 77 and 78: the existence of both physisorbed a
Page 79 and 80: decomposition products (Hf-H) and g
Page 81 and 82: dried by ultra high purity N2 gas.
Page 83 and 84: pressure for XPS analysis is around
Page 85 and 86: Hf and N elements, incorporation of
Page 87 and 88: [150,151] This is a unique feature
Page 89 and 90: software. The thickness results are
Page 91 and 92: CHAPTER 4. DIRECT LIQUID INJECTION
Page 93 and 94: film growth region. The properties
Page 95 and 96: solution was accurately controlled
Page 97 and 98: size). For the rocking curve analys
Page 99 and 100: oxygen does not participate in the
Page 101 and 102:
ecause vapor velocity cannot be cha
Page 103 and 104:
Fig. 40. Cross-sectional view by fi
Page 105 and 106:
the MgAl2O4 substrate confirms cube
Page 107 and 108:
pattern. Fig.44(b) has diffraction
Page 109 and 110:
We have used an AGM (Alternating Gr
Page 111 and 112:
as derived equations for different
Page 113 and 114:
deposited at 600˚C is the lowest.
Page 115 and 116:
wave states degenerate with the FMR
Page 117 and 118:
Fig. 53. ϕ-scan of nickel ferrite
Page 119 and 120:
Surface roughness characterized by
Page 121 and 122:
Fig. 56. X-ray diffraction θ-2θ c
Page 123 and 124:
4.4 Conclusion In summary, we have
Page 125 and 126:
CHAPTER 5. DIRECT LIQUID INJECTION
Page 127 and 128:
eaction zone of the tube furnace is
Page 129 and 130:
Fig. 58. X-ray diffraction characte
Page 131 and 132:
interface. This phenomenon probably
Page 133 and 134:
6.1 Conclusion CHAPTER 6. CONCLUSIO
Page 135 and 136:
the temperature range of 600˚C to
Page 137 and 138:
such as PMN-PT and PZN-PT. CVD proc
Page 139 and 140:
[18]. L. S.-J. Peng, X. X. Xi, B. H
Page 141 and 142:
[54]. B. O. Johansson, J. -E. Sundg
Page 143 and 144:
[96]. J. D. Adam, S. V. Krishnaswam
Page 145 and 146:
[136]. J. Zhao, V. Fuflyigin, F. Wa
Page 147 and 148:
APPENDIX A: LabVIEW PROGRAM FOR PEA
Page 149 and 150:
APPENDIX B: TDMAH MOLECULAR STRUCTU
Page 151 and 152:
H 18 B19 2 A18 1 D17 H 18 B20 2 A19
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